A Havenworlder exploration vessel is exchanging stuff and ideas with a Terran exploration vessel. All is relaxed and going very well until one of the Terrans puts down their drinking vessel and declares the most terrifying words in all the multiverses -- "I've just had a thought!!" -- Anon Guest
Humans are Deathworlders. They have become gradually aware of this. Deathworlders and Havenworlders should not mix, but space is an unfriendly environment and sometimes you really need a big friend who is meaner to the environment around you than it could possibly be to you. Humans have had practice with being kind to smaller and more fragile lifeforms, and actually understand that Havenworlders were not meant for the large and cruel universe.
As a bonus, Humans can, have, and will see off bigger and meaner Deathworlders. This is why Humans are recommended companions for travel anywhere. Humans are also recommended as trading partners, since they will find alternate uses for literally anything.
This is not to say that interactions with Humans are safe. Humans have their own inherent and endemic risks, as documented by the crew of the Poke and See. They had successfully negotiated some trades and, while assorted crew were waiting for the fabricators to finish, the Humans insisted on a group bonding ceremony known as a Potluck Dinner.